Paper feeding device

ABSTRACT

A paper feeding device includes a rotational axis with a groove shaped cross section and having a web extending in the longitudinal direction and a flange provided at opposite sides thereof, and a pickup roller having a concave groove to receive the rotational axis. One end of the pickup roller is provided with a pair of engaging pieces that engages with a flange end portion of the rotational axis respectively, and the other end of the pickup roller is provided with a hook that is inserted into an insertion hole provided on the web of the rotational axis. In the paper feeding device, detachment is easy when the pickup roller is to be replaced and there is no increase in the number of parts and manufacturing processes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a paper feeding device with a pickup roller that feeds a sheet of paper in a printer or a copying machine.

2. Description of the Background Art

In a printer or a copying machine, a pickup roller is used to feed a sheet of paper. In a commonly used pickup roller, the surface thereof is formed of an elastic and anti-slip material such as rubber. The pickup roller is rotated to feed a sheet of paper. The surface of the pickup roller formed of rubber and the like gradually wears by the repeated operation of paper feeding. Therefore, the pickup roller needs to be replaced regularly.

The pickup roller is rotary driven by a rotational axis. If the rotational axis is provided so as to penetrate the pickup roller, the rotational axis itself needs to be detached when the pickup roller is to be replaced. An end of the rotational axis is provided with means for transmitting driving force of a gear or a pulley to drive the rotational axis. Accordingly, it is not easy to detach the rotational axis that retains the pickup roller.

Thus, a structure that allows the pickup roller to be replaced without detaching the rotational axis is proposed. In the structure shown in FIG. 7 and described in Japanese Patent Laying-Open No. 10-236673, a pair of collars 72 is provided that is penetrated by a rotational axis 71. The surface of collars 72 facing a pickup roller body 74 is provided with a rectangular axial member 73 and the corresponding part of pickup roller body 74 is provided with a rectangular concave portion 75. When pickup roller body 74 is to be replaced, one of the pair of collars 72 is shifted axially and the pickup roller body is also shifted in the same direction. Thus, rectangular axial member 73 is disengaged from concave portion 75 so that fixation of pickup roller body 74 is released. Thus, pickup roller body 74 can be replaced without detaching rotational axis 71.

In the structure shown in FIG. 8 and described in Japanese Patent Laying-Open No. 04-075934, rotational axis 81 is provided with a pair of rectangular holes 85 and a pair of round holes 86. Pickup roller 82 is provided with a pair of engaging pieces 83 and a pair of positioning pins 84 at respective corresponding positions.

When pickup roller 82 is to be mounted, positioning pin 84 of pickup roller 82 is inserted into round hole 86 to position pickup roller 82. By the insertion, engaging piece 83 engages with rotational axis 81 so that pickup roller 82 is fixed to rotational axis 81. For a removing operation, pickup roller 82 can be removed by pulling pickup roller 82 to pull out positioning pin 84 while releasing engagement of pair of engaging pieces 83.

In the mounting structure of the pickup roller described in Japanese Patent Laying-Open No. 10-236673, there is a problem of increase in the number of parts since the pickup roller is formed of three parts, i.e. pickup roller body 74 and the pair of collars 72 provided at opposite sides thereof. Further, there is also a problem of increase in the number of manufacturing processes, since the pair of collars 72 needs to be mounted to rotational axis 71 and then pickup roller 74 needs to be mounted to the mounted pair of collars 72 when manufacturing a printer and the like.

In the mounting structure of the pickup roller described in Japanese Patent Laying-Open No. 04-075934, there is a problem of difficulty of operation and reduced working efficiency since both of positioning pins 84 must penetrate respective round holes 86 of rotational axis 81 simultaneously.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a paper feeding device in which detachment is easy when a pickup roller is to be replaced and that does not increase the number of parts and manufacturing processes.

A paper feeding device according to the present invention includes a rotational axis with a groove shaped cross section having a web extending in the longitudinal direction and a flange provided at opposite sides thereof, and a pickup roller having a concave groove to receive the rotational axis. An end of the pickup roller is provided with a pair of engaging pieces that engages with a flange end portion of the rotational axis respectively, and the other end of the pickup roller is provided with a hook that is inserted into an insertion hole provided on the web of the rotational axis.

Preferably, in the paper feeding device, the hook extends outwardly from the body of the pickup roller and forms a stepped shape having an abutting surface that abuts against the inner surface of the web.

Preferably, in the paper feeding device, a notch for positioning is provided at a site in the flange end portion where the engaging piece engages.

Further, preferably, in the paper feeding device, the engaging piece of the pickup roller is formed of resin and an end of the engaging piece is made to engage with the flange end portion by elasticity of resin.

In the paper feeding device of the present invention, detachment is easy when the pickup roller is to be replaced and there is no increase in the number of parts and manufacturing processes.

The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view from one end of a pickup roller in an embodiment according to the present invention.

FIG. 2 is a perspective view from the other end of the pickup roller in an embodiment according to the present invention.

FIG. 3 is a front view of a rotational axis in an embodiment according to the present invention.

FIG. 4 is a front view showing a process in which the pickup roller is attached to the rotational axis.

FIG. 5 is a front view showing a state in which the pickup roller has been attached to the rotational axis.

FIG. 6 shows the pickup roller in a used state in an embodiment according to the present invention.

FIG. 7 is a perspective view of a mounting structure of the pickup roller in the prior art.

FIG. 8 is a perspective view of the mounting structure of the pickup roller in the prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A paper feeding device in one embodiment of the present invention now will be described referring to FIGS. 1-6.

A paper feeding device of the present embodiment includes a rotational axis 41 with a groove shaped cross section, and having a web 41 w extending in the longitudinal direction and a flange 41 f provided at opposite sides thereof. The paper feeding device further includes a pickup roller 1 having a concave groove 25 to receive rotational axis 41. One end of pickup roller 1 is provided with a pair of engaging pieces 21 that engages with an end portion of flange 41 f of pickup roller 1 respectively, and the other end of pickup roller 1 is provided with a hook 15 that is inserted into an insertion hole 43 provided on web 41 w of rotational axis 41. Hook 15 extends outwardly from a pickup roller body 11 and has a stepped shape having an abutting surface 15 a that abuts against the inner surface of web 41 w. A notch 45 for positioning is provided at a site in an end portion of flange 41 f where engaging piece 21 engages. Engaging piece 21 of pickup roller 1 is formed of resin so that an end of engaging piece 21 is made to engage with notch 45 of the end portion of flange 41 f by elasticity of resin.

Pickup roller 1 is formed of a body 11 of pickup roller of synthetic resin, and a non-slip material 31 of rubber provided on the perimeter thereof. Non-slip material 31 occupies about two-thirds of the area of the perimeter surface of pickup roller body 11. As shown in FIG. 6, non-slip material 31 is pressed against the surface of a sheet 53 of paper and sends out sheet 53 in the paper feeding direction when pickup roller 1 is rotated. Thus, a material that has a certain degree of elasticity as well as frictional force with respect to a sheet of paper is selected.

Pickup roller body 11 serves to retain non-slip material 31 and is fixed to rotational axis 41. Pickup roller body 11 is provided with concave groove 25 extending to the center of pickup roller body 11. Concave groove 25 also extends in the longitudinal direction (the axial direction) of pickup roller body 11 and is exposed at the opposite sides thereof as shown in FIGS. 1 and 2.

One end of pickup roller body 11 is provided with pair of engaging pieces 21. As shown in FIG. 1, engaging pieces 21 are formed as a cantilever that are pendent downwardly from opposite sides of a base portion 22 protruding horizontally from an end surface of pickup roller body 11. As shown in FIG. 1, the end portion of engaging piece 21 has a crochet hook shape and the end portion engages with the end portion of flange 41 f of rotational axis 41 from the outside. Pickup roller body 11 and engaging piece 21 are formed of synthetic resin so that the end portion of engaging piece 21 can be made to engage with flange 41 f of rotational axis 41 by elasticity of resin.

The other end of pickup roller body 11 is provided with hook 15, as shown in FIG. 2. Hook 15 is formed to have a stepped shape protruding outwardly from pickup roller body 11. With pickup roller body 11 mounted to rotational axis 41, the upper surface of an end portion of hook 15 forms an abutting surface 15 a that abuts against the inner surface of web 41 w of rotational axis 41.

Rotational axis 41 shown in FIG. 3 is made of metal and includes web 41 w and flange 41 f provided at opposite sides thereof and has a groove shaped cross section. A paper feeding cam 47 formed of synthetic resin is provided at opposite ends of rotational axis 41. Near the center of rotational axis 41 is provided an insertion hole 43 into which hook 15 of pickup roller body 11 is inserted. Insertion hole 43 is formed as a rectangular hole provided on web 41 w. Further, at a position in the end of flange 41 f away from insertion hole 43 by a predetermined distance is provided a notch 45 where engaging piece 21 of pickup roller 1 engages to determine an engaging position of engaging piece 21.

Then, a procedure to mount pickup roller 1 to rotational axis 41 will be described. First, as shown in FIG. 4, hook 15 of pickup roller 1 is inserted into insertion hole 43 of rotational axis 41. Next, mounting of pickup roller 1 is completed by pressing down the opposite side of pickup roller 1 to engage engaging piece 21 with notch 45 of the end of flange 41 f from the outside. Thus, in the pickup roller 1 of the present embodiment, pickup roller 1 can be mounted very easily.

In the mounting structure of the pickup roller described in Japanese Patent Laying-Open No. 04-075934, it is necessary to insert a pair of positioning pins into the rotational axis simultaneously, rendering positioning very difficult. However, in pickup roller 1 of the present embodiment, hook 15 is latched into rotational axis 41 and then engaging piece 21 of the opposite side is engaged so that the positioning is completed by just inserting hook 15 into insertion hole 43. Thus, pickup roller 1 can be mounted to rotational axis 41 very easily. This effect is evident in the process where pickup roller 1 is replaced as well as in the process where pickup roller 1 is mounted to rotational axis 41 in manufacturing a printer and the like.

Further, rotational axis 41 is provided with notch 45 where engaging piece 21 engages so that pickup roller 1 can be positioned more securely. More specifically, as shown in FIG. 4, in pickup roller 1 of the present embodiment, hook 15 is inserted into insertion hole 43 from an oblique direction. Accordingly, insertion hole 43 needs to have some play. The end portion of engaging piece 21 of pickup roller 1 and notch 45 are formed to exactly fit together so that backlash of pickup roller 1 after installing can be eliminated. It is to be noted that notch 45 may be omitted and engaging piece 21 may directly engage with the end of flange 41 f of rotational axis 41 if backlash of pickup roller 1 after installing is not considered as a serious problem.

When pickup roller 1 is to be removed, first the side of engaging piece 21 is pulled upwardly. At this stage, the engagement can be easily released since engaging piece 21 engages through elasticity of resin. Then, hook 15 is pulled out from insertion hole 43 to complete the removal. Thus, pickup roller 1 can be removed very easily, too.

Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims. 

1. A paper feeding device including a rotational axis with a groove shaped cross section and having a web extending in a longitudinal direction and a flange provided at opposite sides thereof, and a pickup roller having a concave groove to receive said rotational axis, wherein an end of said pickup roller is provided with a pair of engaging pieces that engages with a flange end portion of said rotational axis, another end of said pickup roller is provided with a hook that is inserted into an insertion hole provided on said web of said rotational axis, said hook extends outwardly from a body of said pickup roller and has a stepped shape having an abutting surface that abuts against an inner surface of said web, a notch for positioning is provided at a site in said flange end portion where said engaging piece engages, said engaging piece of said pickup roller is formed of resin and an end of said engaging piece is made to engage with said notch of said flange end portion by elasticity of resin.
 2. A paper feeding device including a rotational axis with a groove shaped cross section and having a web extending in a longitudinal direction and a flange provided at opposite sides thereof, and a pickup roller having a concave groove to receive said rotational axis, wherein an end of said pickup roller is provided with a pair of engaging pieces that engages with a flange end portion of said rotational axis, another end of said pickup roller is provided with a hook that is inserted into an insertion hole provided on said web of said rotational axis.
 3. The paper feeding device of claim 2, wherein said hook extends outwardly from a body of said pickup roller and has a stepped shape having an abutting surface that abuts against an inner surface of said web.
 4. The paper feeding device of claim 2, wherein a notch for positioning is provided at a site in said flange end portion where said engaging piece engages. 